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Managing Corn Rootworm in High-Pressure Fields

Categories: GROWING, CORN

Late June through mid-July is the time to start monitoring corn rootworm and taking corrective action as needed. Continuous corn and overreliance of a single management practice has expanded resistant corn rootworm populations. Corn rootworm costs corn farmers an estimated $1 billion profit in lost yields and control measures each year.

​​​​Corn Rootworm Life Cycle
As shown in the corn rootworm management and life cycle graphic below, larval hatch has adapted to extend from late May to mid-June. Rootworm larvae go through 3 instar stages before pupating when they stop feeding on roots. July is when farmers need to monitor for adults feeding on silks and in mid-July starting egg lay. Starting in mid-July, a single adult female can lay up to 500 eggs and create excessive pressure in subsequent years. In continuous corn, keep adult beetle numbers below the threshold of 1 insect per plant.

Monitoring Corn Root Damage

Preventing excessive pressure is the key to successful rootworm management. In continuous corn, dig several plants to determine if additional control measures are needed for the current cropping year. Studies have shown a 15 to 18% yield loss when one full brace root node is pruned within one-half inch of the base of the plant. Allowing 2 or more nodes to be pruned greatly impacts water and nutrient uptake, potentially resulting in severe lodging and creating a difficult harvest.

Managing High-Pressure Fields
For fields with historic corn rootworm pressure, a more aggressive management plan may be needed to minimize damage and maximize yield.
  • The most effective management strategy is non-host crop rotation
  • When crop rotation is not an option, use soil-applied insecticides with a pyramidal trait stack to protect roots and enhance yield1 
  • Use foliar insecticides to minimize egg laying and protect silks during pollination
  • Along with crop rotation, rotate pyramidal trait stacks, such as Agrisure Duracade® and Agrisure Duracade 5222 E-Z Refuge®, the most advanced trait stack on the market to reduce the likelihood of resistance

Planting a trait stack with corn rootworm control can make a difference in not only root size, but also ear size. The root and ear pictured on the left contains an Agrisure Duracade trait stack, while the one on right does not. 

Contact your Golden Harvest Seed Advisor with questions or for additional agronomic insights.
1There is no evidence to indicate that the use of a soil-applied insecticides on CRW traits will either slow or hasten resistance development to CRW traits. 

Photos are either the property of Syngenta or used under agreement.

Syngenta hereby disclaims liability for third-party websites.

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